Solar EV charging guide for New Zealand. We can supply different EV chargers that are capable of diverting excess energy from your solar setup in to your car battery. 

Charging at home with Solar

Charging using solar is as simple as charging your car while you are generating power using your solar. 

This can be done manually with your standard 8a granny charger or faster with a 16a charger with a caravan plug. However if you want to get the most out of your solar you are best to use one of our wall chargers that can vary its output to either pick up any excess power going to the gird. Or to match the rate the car is charging with the output of the inverter. 

How does Solar EV charging work?

Typical home solar and ev charging setup showing ct clamps

A typical Solar EV charging setup is shown above. A CT clamp is installed on either the output of the inverter or on the main cable coming in to the house. The charger can then see what direction the current is flowing and determine how much current is flowing. 

Based on this the charger will vary the current going to the car to ensure no excess electricity is going out to the grid and its all being consumed. 

Our Smart EV charger branded charger has the CT clamp installed on the output of the inverter (CT2 in the above image). If you solar is generating say 16a or 3.5kW then the same amount is put in to the car. Using this method there is never any excess power going back out to the grid. 

The Autel Series charger works a little differently, the CT clamp is measuring the current and direction at the CT1 position. So if you solar is generating 16a or 3.5kW and your house is using 1.75kW, then the leftover 1.75kW will go in to the car. 

 

What is the minimum rate an EV can charge from Solar?

EV charging using solar graphThe minimum charge a car can take before it will switch off is 6 to 8 amps depending on the car or 1.3kW. If the charge falls below this the EV charger will either shut off, or use some power from the grid to maintain charging at a minimum rate. 

To avoid constantly switching on and off when the solar generation drops down, most EV chargers will maintain the 6amps minimum from the grid. Every charger is different. Some will shutoff after x amount of time with low power to minimise power draw from the grid.

To avoid charging using the grid a timer can be set on the charger to charge while the sun is shining. 

How long will it take to charge my car using solar?

 

Calculating the charge time using Solar.  

Charging using solar is no different from charging using your standard power. The rate of charge depends on the following variables. 

  1. The size of your solar setup

  2. The size of your car battery and its current state of charge

  3. How much power your solar energy your house uses. 

You can use our EV charging calculator to work out the charge time. Input the charge current.
This should be how much solar your system is capable of producing or the excess solar that you export. 

Example: 
7kW system can produce 32a
4.4kW system can produce 18a
3.5kW system can produce 16a

The average size solar setup in New Zealand is 4.4kW base on information from the Electricity Authority

Solar EV charge time Calculator

Inputs
Current:
Car Battery Size (kWh):
Current State of Charge:
Output
Estimated Time to Charge:
(Hours: Min)

EV charging Speed and efficiency

It is more efficient to charge your car faster at 7kW or 32a than it is to trickle charge at 10a or 2.4kW . 

Testing has shown that charging a BYD using a granny charger is around 87% efficient. Where as when charging between 16a and 32a the efficiency is around 91%. 

This is because there are losses in the system. If you are charging for longer the battery management system and cooling system is running for longer. These use power. As does the A.C to D.C converter in the car. 

This is why we recommend using a dedicated wall charger that has solar diversion capabilities over the standard plugin charger. 

 

Our Solar Capable Chargers

Original price was: $799.00.Current price is: $680.00.

Smart EV Chargers

Starting with our Smart EV charger brand of charger. These are avaiable in socket version or with a Type 2 cable attached.  
These have 2 Modes. 

ECO mode: This will divert all avaiable solar in to the car and vary the charge based on avaiable solar generation. When the solar drops off it will maintain charging with the minimum of 6a to keep the car awake and to avoid switching on and off. 

Standard mode: This will ignore what your solar is doing and provide you with the fastest charge possible to get you moving. 

Autel Series Chargers

When paired with the Energy meter the Autel charger can monitor excess solar thats being generated and use this to charge the car. It has 3 modes. 

Green Mode – Only using excess energy

Green Priority – Using the excess energy + an additional top up of 6a from the grid when there is no sun.

Speed Priority – Full speed charging.